Bathroom reno sheeting order and waterproofing?

[user455828]

A few questions team!

Water proof yellow tongue or sheet over with tile underlay then waterproof? 

Does the order of sheeting matter? Eg walls first then floor? 

[MitchellMc]

Welcome to the Bunnings Workshop community @user455828. It's brilliant to have you join us, and many thanks for your question about bathroom renovations.

If your bathroom floor is yellow tongue, you wouldn’t normally waterproof directly over it — the better approach is to lay a suitable tile underlay sheeting over the top, then apply your waterproofing membrane. Mechanical fixings and acrylic stud adhesive are used to connect the cement sheeting to the structural flooring. This creates a stable, water-resistant base that won’t swell if any moisture gets through. 

For the sheeting order, it's better to do the floor first. That way, the wall sheets come down and sit on top of the floor sheets, creating a continuous, sealed junction at the wall-to-floor connection and avoiding any gaps. Once all sheeting is in place, you can apply the waterproofing membrane over both walls and floor.

Here's the installation guide for James Hardie Ceramic Tile Underlay.

Please let me know if you have any questions.

Mitchell